More particularly, the invention relates to a flying vehicle including first and second rotors respectively mounted in rotation about first and second axes of rotation, the first rotor including a first group of blades extending in a first blade plane and the second rotor including a second group of blades extending in a second blade plane, the first and second rotors each being driven into rotation by driving motor means of the machine.
Flying vehicles having two counter-rotating rotors have the advantage relatively to flying vehicles with only one rotor with a vertical axis (conventional helicopters) of not requiring an anti-torque additional rotor for controlling the yaw generated by the rotation of the rotor with a vertical axis.
A vehicle of the prior art of the type defined earlier is, for example, shown in FIG. 1. This vehicle includes two rotatably mounted rotors about two coinciding axes of rotation. Each of these rotors bears a group of blades with variable pitches.
The vehicle includes a single motor for driving into rotation each of the two rotors, one of the rotors having a hollow shaft in order to let through the shaft for driving into rotation the second rotor in this hollow shaft, both of the shafts rotating in opposite directions.
In this context, the object of the present invention is to propose a flying vehicle with two rotors having increased maneuverability as compared with the flying vehicle of FIG. 1.
For this purpose, the flying vehicle of the invention moreover according to the generic definition given by the preamble as defined earlier, is essentially characterized in that said driving means include at least one motor positioned between said rotors and between said first and second blade planes.
The fact of placing the motor between the rotors and between the blade planes allows the centre of gravity of the vehicle to be brought closer to the space located between the first and second blade planes and the axes of rotation of the rotors.
Further, the masses of the vehicle are thus brought closer to its centre of gravity which is located between the rotors and in proximity to the axes of rotation of the rotors. The inertia of the flying vehicle relatively to its centre of gravity is therefore reduced thereby improving the maneuverability of the vehicle.
By means of this relatively high and centered position relatively to the rotors of the centre of gravity, the maneuverability of the vehicle is improved. Further, the fact that the motor is found between the blade planes of the rotors, allows reduction in the wind resistance of the vehicle outside the space between the blade planes, the result of this is increased stability of the vehicle to lateral wind gusts.
It is also possible to ensure that said at least one motor has a size and a location such that it (the motor) is comprised inside a cylinder-shaped space with maximum volume coaxial with said first axis of rotation and with a radius of less than two thirds of the length of a blade of said first rotor.
By this definition of the maximum volume of the motor, it is possible to specify its maximum size and its location opposite to the first rotor so as to obtain a sufficiently maneuverable flying vehicle.
The space located between the rotors at their respective peripheries (i.e. at the ends of the blades) is free of any obstacle so that an airflow may circulate between the rotors in a direction parallel to at least one of the planes of the rotors (this flow notably exists during horizontal displacements of the flying vehicle).
It is also possible to ensure that the motor further includes a case encompassing said driving means of the vehicle, this case being comprised in said maximum volume space with a cylindrical shape.
The use of the case which is preferentially aerodynamic allows increase in the yield of the rotors in terms of vertical thrust by limiting the perturbations between these rotors which are caused by the presence of the driving means.
For example, it may be ensured that the blades borne by the rotors are blades with variable pitches.
By positioning the motor between the blade planes, it is easier to control the tilt of the blades since the blades of both rotors are accessible from the space between the blade planes without having to use a blade pitch control mechanism passing through a rotor in order to control the pitch of the blades of the other rotor.
For example, it may be ensured that said first rotor includes a first crown which extends around said first axis of rotation and which is bound in rotation about the first axis of rotation relatively to said first group of blades while being mobile relatively to the first group of blades, at least some of the blades of the first group of blades being mechanically connected to said first crown so that the relative displacement of this first crown relatively to the first group of blades causes a change in incidence of the blades mechanically connected to said first crown, relatively to said first axis of rotation.
For example, it may be ensured that said second rotor includes a second crown which extends around said second axis of rotation and which is bound in rotation about the second axis of rotation relatively to said second group of blades while being mobile relatively to the second group of blades, at least some of the blades of the second group of blades being mechanically connected to said second crown so that the relative displacement of the second crown relatively to the second group of blades causes a change in incidence of the blades mechanically connected to said second crown, relatively to said second axis of rotation.
The incidence of a blade relatively to the axis of rotation of the rotor, to which this blade belongs, is the pitch of this blade. This pitch allows determination of the lifting force generated by this blade during the rotation of the rotor. The use of a crown for controlling the incidence of the blades of a rotor is advantageous since it is possible to control the pitch of each blade during its rotation and therefore the lift of the rotor by orienting and positioning this crown relatively to the blade plane of the rotor to which it belongs.
It is therefore possible to control the collective pitch of the blades of this rotor and/or the individual pitch of each blade of this rotor by simply positioning the crown.